From a genealogy perspective, maps help us to pinpoint where our ancestors lived. We can get a sense of the terrain as well as how rural or urban the area might have been. We can use maps to track how far our ancestors moved throughout their lives. Often we find that even thought they might have moved several times to get employment, they rarely left a small radius of 5 or 10 miles.
The National Library of Scotland has over 2.5 million maps in their collections. And they have the best online collection of digital maps bar none. Their collections include estate maps, town plans and maps, military maps, county and country maps.
Estate maps can show the farms your ancestors lived and worked on. We can see quarries, coal mines, forests, lochs, farm fields and location of the buildings belonging to the estate.
Town plans and maps show us how densely populated the town or village was and often will have labels on the buildings. These labels may determine the type of building, or they may be the name of the building's owner or proprietor. Military maps can show us the early roads leading to the area where your ancestor lived.
Currently, the National Library of Scotland has an exhibit about Maps. It is a wonderful exhibit.
Here is a preview:
1580 map of Scotland (Scotiae tabula) by Abraham Ortelius
1780 map of the City of Edinburgh by John Ainslie